1. Field of the Invention
The present invention relates to polymer compositions and shrink films having biodegradability. More particularly, the present invention relates to biodegradable polymer compositions and biodegradable shrink films which comprise polylactic acid mixed with another polyester type biodegradable polymer, can decompose substantially completely, and have improved physical properties.
2. Description of the Related Art
Most of conventional biodegradable polymer compositions comprise one kind of biodegradable polymer as a main component and further contain one or more additives such as plasticizers. Therefore, the physical properties are often governed by the main component polymer and some additives must be added in order to further improve the physical properties.
Hitherto, heat shrink films conventionally used for packaging and the like are mainly of polyvinyl chloride, polyethylene terephthalate or polystyrene type resins. However, shrink films made of such resins increase the amounts of refuse upon disposal and remain in the earth semipermanently when buried therein or affect the landscape adversely when left on the ground. Until now, no shrink film has been provided which decomposes under the natural environment. Thus, biodegradable polymers have recently attracted attention to solve these problems.